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On 23 June, 2020, a magnitude 7.4 subduction earthquake struck western Mexico and let the earthquake early warning sirens sound in the capital. Reportedly, ten people lost their lives and thousands of houses were damaged in Oaxaca. Our colleagues Magda Velázquez-Bucio, Sabina Porfido, and Alessandro Michetti have put together a report on the Earthquake Environmental Effects of this event in English and Spanish:

Ho, ho, ho! Merry Christmas, everybody. Have a joyful season and a happy, happy, happy new year! In case you’ve forgotten (over eating and drinking): Today is Friday and here are your links!

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The 2011 Christchurch earthquake series had severe consequences and surprised scientists for many reasons. Ground motions were extremely strong despite the relative moderate magnitudes of the quakes (M_W 5.3-7.1). The events happened on a system of hitherto unknown faults, some of which are located directly below Christchurch. Earthquake environmental effects (EEE), especially liquefaction, were intense and widespread. It turned out that subsequent quakes reactivated the same feeder dikes of sand blows, showing that saturated sediments are susceptible of liquefaction no matter if they had been liquefied recently (also see the paper of Quigley et al. (2013) on the liquefaction effects). Another stunning lesson was the occurrence of intense rockfall in the vicinity of Christchurch. In a recently published study, Mackey and Quigley (2014) dated rockfall boulders with ³He and show that they allow to estimate the recurrence intervall of local seismic events like the 2011 series. This works is a very interesting way to use EEE for paleo-earthquake studies. more

Today’s post of the Landslide Blog about a rockfall caused by a volcanic earthquake reminds me about something that’s in my mind for years already. Could we use dust deposits as a paleoseismological archive? Dust clouds of all sizes, ranging from tiny to huge, can be associated with seismic shaking, especially in arid and mountainous regions. Here I have collected a few videos I found on YouTube. When large amounts of dust settle they should form a distinctive layer recognizable in the sedimentary record, comparable to volcanic ash deposits. Of course they will be harder to be identified, since the material is the local one. I guess this could be done, similar to turbidites in marine paleoseismology. There are papers that describe changes in the aerosol content in the atmosphere after earthquakes, so why not look for them on earth? more

Let’s see, this is my 1st post here, thanks again for the invitation. Today, an interesting story circulated through mass and science media. The article by Kremer et al. published yesterday in Nature Geoscience presents geophysical and sedimentological evidence of potential tsunamis in the rather exotic environment of Lake Geneva. This phenomenon is not new at all and has been investigated by others before, but I pretty much share the authors conclusion, that the hazard of tsunami-like events in continental lakes deserves higher attention in the future.

The Gulf Stream is ensuring the mild climate in Europe, everyone knows that. But does it really? Read Chris Rowan’s article on climate, Gulf Stream, heat capacity and atmospheric circulations.

Ritz et al. published a paper on the paleoseismicity of the North Tehran Fault, Iran. From trenching studies they claim at least 6 surface-rupturing events during the last 30 ka. Read the paper here at JGR-Solid Earth. Ritz, J.-F., H. Nazari, S. Balescu, M. Lamothe, R. Salamati, A. Ghassemi, A. Shafei, M. Ghorashi, and A. Saidi, 2012: Paleoearthquakes of the past 30,000 years along the North Tehran Fault (Iran), J. Geophys. Res., 117, B06305, doi:10.1029/2012JB009147. more